The Grand River at Comstock Park rose to 12.5 feet shortly before 9:30 a.m. Thursday, up from about 11 feet overnight. Forecasters say Abrigador Trail will be underwater at 13 feet, with some isolated flooding of homes should additional rising occur.

Ice jams help cause rapid fluctuations in river levels by suddenly releasing water when they break and move downstream. This is being recorded from observers at the river and from instrumentations, said Jared Maples, a meteorologist at the National Weather Service in Grand Rapids.

Already, the river has fallen off some to 12.4 feet at 9:53 a.m.

"That kind of just shows you the potential these ice jams have to cause this rapid fluctuation," Maples said.

The Weather Service has requested the Grand Rapids Police Department to keep an eye on the area and control traffic should the water rise any further, Maples said. So far, no flooding of any homes or other buildings has been reported.

Andrew Krietz covers breaking and general police/fire news for MLive | The Grand Rapids Press. Email him at akrietz@mlive.com or follow him on Twitter.